1. Field of the Invention
The present invention relates to motors of the type having an oscillating or vibrating armature capable of providing a reciprocating motion to a load attached thereto.
2. Description of the Prior Art
Vibrating motors are well known in the art and are widely used in devices requiring a reciprocating action as opposed to a rotating action. Examples of such devices include dry shavers, hair clippers, massagers, sanders, engravers and certain types of pumps. The typical motor of this type comprises a stator assembly, which is held in a stationary position with respect to the housing of the device, and an armature assembly, which is attached to the housing of the device and which is allowed to move in a vibrating relation to the stator assembly. The load requiring the reciprocating motion, for example, the blade of a hair clipper, is therefore typically attached to the armature of the motor.
The stator and armature assemblies may be formed from a plurality of laminations composed of a material capable of conducting a magnetic flux, which are riveted or form fitted together. Steel is commonly used for this purpose. The stator is usually formed in the shape of a "U" or an "E," with the ends of the legs of the stator forming magnetic poles having pole faces thereon. The stator further comprises one or more coils of insulated wire wound around one or more legs thereof. Introducing an electrical signal into the coil of wire will cause a magnetic flux to be induced into the core of the stator, which is formed by the stack of laminations.
The armature of the motor is shaped in a manner complimentary to that of the stator, with an equal number of poles, also having pole faces. The stator and armature are mounted such that the pole faces of the armature face the poles faces of the stator, separated by an air gap. The armature may be held in its resting position by a resilient means, such as a spring, which will maintain the air gap between the pole faces of the armature and the poles faces of the stator. As is well known by those of ordinary skill in the art, the stator and armature pole faces attract each other, closing the air gap, when the core is magnetized by introducing an electric current into the windings. An alternating current (AC) signal will induce a magnetic flux into the core of the stator and armature and a magnetic field into the air gap. This causes the poles of the armature and the stator to be drawn together and the armature to bias the resilient means. During each half of the AC signal cycle, as the voltage increases, the strength of the magnetic field induced into the air gap increases, and the stator and armature are drawn together, compressing the spring. As the voltage decreases, the magnetic field weakens, thereby allowing the spring to return the armature to its resting position. Thus, it can be seen that the armature will vibrate at a rate twice that of the frequency of the AC current signal introduced into the windings. Preferably, the pole faces of the stator and armature never touch each other.
One problem encountered in the manufacture of the reciprocating motor of the prior art is that several adjustments need to be made to each unit, which increases the manufacturing time, and, therefore, the manufacturing cost. Typically, an adjustment will be made to adjust the position of the armature with respect to the stator, and a second adjustment will be made to set the tension on the spring. The object of the adjustments will be to keep the armature and stator from contacting each other while the armature is vibrating, and to minimize the noise and vibration generated by the motor. Typically, several iterations of adjustments will need to be made, since making one adjustment will affect the other adjustment point.
Accordingly, it is desired to provide an improved design for a reciprocating or vibrating motor which will eliminate the need to perform the labor-intensive and time consuming adjustments necessary with the current design.